If as implied by your profile you are using XL2003 then
a) you will need to persist with an Array / SUMPRODUCT rather than use the likes of COUNTIFS introduced in XL2007
b) you will need to avoid use of entire column references (A:A) given they are not permitted pre XL2007 in conjunction with the above
For sake of performance in Excel you should keep your Array ranges as lean as possible - I can't vouch for the same in Google Spreadsheet as I don't use it.
Array - confirmed with CTRL + SHIFT + ENTER (not just Enter)
SUMPRODUCT - confirmed with Enter as normal
SUMPRODUCT is not really any more efficient than the Array, however, it has one advantage in so far as it does not require special "Array entry" - ie can be confirmed with Enter alone.
The above fact makes it a little more robust from an end users perspective in so far as should you edit the formula at any time you need not worry about having to remember to reset the array for it to work.
Bookmarks